Method and device for early detection of a rupture in a continuous casting plant

ABSTRACT

A device and method for the early detection of a rupture in a continuous casting plant, in which liquid metal is cast into a chill ( 2 ) and is withdrawn from the chill ( 2 ) in the form of a billet ( 1 ), the temperature of the chill ( 2 ) being measured, and the temperature of the chill ( 2 ) being simultaneously presented with reference to the location at which the temperature was measured and the time over which the temperature was measured.

[0001] The invention relates to a method and a device for the earlydetection of a rupture in a continuous casting plant, in which liquidmetal is cast into a chill and is withdrawn from the chill in the formof a billet, the temperature of the chill being measured. Earlydetection of a rupture is to be understood here as meaning that it isdetected at an early time if there are ruptures of the initially liquidcore of the billet through the solidified shell of the billet. However,for the purposes of the invention, early detection of a rupture is alsoto be understood in principle as meaning the detection of defects in thebillet which could lead to ruptures.

[0002] For the early detection of a rupture, it is known to measure thetemperature of the chill at various points on the chill and to presentthe temperature at the measured points on a display. Such a display isshown, for example, in FIG. 4.

[0003] It is the object of the invention to improve the known earlydetection of a rupture.

[0004] This object is achieved according to the invention by a method asclaimed in claim 1 or 2 and a device as claimed in claim 3 or 4. For theearly detection of a rupture in a continuous casting plant, in whichliquid metal is cast into a chill and is withdrawn from the chill in theform of a billet, the temperature of the chill is measured. The measuredtemperature of the chill is then simultaneously presented and/orevaluated with reference to the location at which the temperature wasmeasured and the time over which the temperature was measured. In thisway, ruptures or defects which may lead to ruptures can be predictedconsiderably better than by the known method.

[0005] Advantages and details emerge from the following description, theprior art and an exemplary embodiment of the invention. In the drawing:

[0006]FIG. 1 shows a continuous casting plant,

[0007]FIG. 2 shows a chill,

[0008]FIG. 3 shows the arrangement of temperature sensors, representedon the basis of a “developed” chill,

[0009]FIG. 4 shows a known visual representation of measured temperaturevalues, and

[0010]FIG. 5 shows a representation of the temperature with reference tolocation and time.

[0011]FIG. 1 shows a continuous casting plant. Represented are a castingladle 4, a distributing launder 3, a chill 2 with temperature sensors 8for temperature sensing, a billet 1, guide rollers 5, a cutting device 6and a slab 7. The arrangement of the temperature sensors 8 on the chill2 is illustrated by FIG. 2. The temperature sensors 8 are connected viaa data line 11 to an evaluation device 10 and a display 9 for presentingthe temperature with reference to time and location.

[0012] Advantageously coming into consideration as temperature sensorsare, for example, thermocouples.

[0013] The early detection of a rupture during the continuous casting ofsteel serves the purpose of detecting defects in the billet shell at anearly time. Defects take the form of stickers and cracks and may lead toa rupture of the billet shell, accompanied by high commercial losses andloss of production.

[0014]FIG. 3 shows a chill 2 in a developed representation. Fitted onthe chill 2 in two rows are about n=20 temperature sensors per row. Theinvention is also used most particularly advantageously with one row oftemperature sensors.

[0015] For the visual representation of the temperature i, a bar chartaccording to FIG. 4 is known. In this, the temperature at the currentpoint in time is indicated for each temperature sensor by means of a barchart, that is to say the current measured values are indicated.

[0016] The basic idea of the method of visual representation proposed bythe invention is the simultaneous representation of location NT,temperature i and time t, as presented in a representation shown by wayof example in FIG. 5. For the two rows of temperature sensors from FIG.3, a visual representation according to FIG. 5 is respectively provided:

[0017] (i) location: the local distribution of the temperature sensorsis presented row by row in the same way as before.

[0018] (ii temperature: in each row, the temperature i is indicated bydistinguishing colors.

[0019] (ii time: the data successively coming in is presented row byrow, so that the time t is represented by going down the rows.

[0020] The temperatures are represented in a particularly advantageousway by different colors. In this case, it is of particular advantage notto allow any continuous differences in color but to assign a specificcolor respectively to specific temperature regions. For reasons ofblack-and-white representation, the colors are represented in FIG. 5 bydifferent shadings. Elements of the same color represent regions of thesame temperature. 5 is a higher temperature than 4, 4 is a highertemperature than 3, 3 is a higher temperature than 2 and 2 is a highertemperature than 1. The joining lines 12, 13, 14, 15, 16 betweenadjacent regions of the same color, so-called isochromes, correspond tolines of the same temperature, i.e. so-called isotherms. Vertical lines,i.e. vertical isochromes, are to be interpreted as undisturbedsteady-state operation of the continuous casting plant.

[0021] When the defects mentioned above occur, characteristic isochromesform and are easily identifiable for the operator of a continuouscasting plant in this form of visual representation. The pattern of theisochromes 12 and 16 indicated in FIG. 5 (top left) shows a region inwhich a defect has formed with increased temperature, as ischaracteristic in the case of stickers. The temperature is highest inthe interior of the time/location distribution and decreases toward theedges.

[0022] On the same principle, with a converse temperature gradient,there is shown in FIG. 5 (center) a pattern of the isochromes 13, 14, 15with lower temperature in the interior, as occurs in the case of cracks.

[0023] In a refinement of the invention, the representation according toFIG. 5 is presented on the display 9. However, the invention is alsosuitable particularly advantageously for the automatic detection oflikely defects in the billet which may lead to a rupture. In this case,the representation according to FIG. 5 is not presented on a display butis fed to an automatic pattern detection, which emits an alarm when asignificant defect is detected.

[0024] The pattern detection is implemented particularly advantageouslyon an evaluation device 10. It is particularly advantageous,furthermore, to present a pattern detection on an evaluation device 10and simultaneously a graphic representation, as shown by way of examplein FIG. 5, on a display 9.

1. A method for the early detection of a rupture in a continuous castingplant, in which liquid metal is cast into a chill (2) and is withdrawnfrom the chill (2) in the form of a billet (1), the temperature of thechill (2) being measured, and the temperature of the chill (2) beingsimultaneously presented with reference to the location at which thetemperature was measured and the time over which the temperature wasmeasured.
 2. A method for the early detection of a rupture in acontinuous casting plant, in which liquid metal is cast into a chill (2)and is withdrawn from the chill (2) in the form of a billet (1), thetemperature of the chill (2) being measured, and the temperature of thechill (2) being simultaneously evaluated with reference to the locationat which the temperature was measured and the time over which thetemperature was measured.
 3. A device for the early detection of arupture in a continuous casting plant, in which liquid metal is castinto a chill (2) and is withdrawn from the chill (2) in the form of abillet (1), the device for the early detection of a rupture having atemperature sensor (8) for measuring the temperature of the chill (2)and a display for simultaneously presentating the temperature of thechill (2) with reference to the location at which the temperature wasmeasured and the time over which the temperature was measured.
 4. Adevice for the early detection of a rupture in a continuous castingplant, in which liquid metal is cast into a chill (2) and is withdrawnfrom the chill (2) in the form of a billet (1), the device for the earlydetection of a rupture having a temperature sensor (8) for measuring thetemperature of the chill (2) and a pattern detection for evaluating thetemperature of the chill (2) with reference to the location at which thetemperature was measured and the time over which the temperature wasmeasured.